The present invention relates to a sandwich element in the form of a slab, shell and the like. The element consisting of facings and a rigid polyurethane foam core based on polyisocyanate, and of edge profiles.
Sandwich elements which are intended to be separably or permanently joined together have problems associated with the airtight and watertight sealing of the joints because of the supporting facings made of aluminum foil, sheet steel, plastic film or composite paper. Conventional bonding with profiles made of suitable materials, such as wood, metal or plastic, is expensive and, because of the low strength of the foam core, very sensitive to impact. Internal stresses result in rapid loosening of the joint between the actual sandwich element and the edge profile. In addition, distortion may occur due to the internal stresses. Differences in coefficients of thermal expansion of the various materials also cause cracking.
The object of the present invention is to provide sandwich elements, which have an optimum stability, with joining means which are airtight, watertight and durable as well as free from distortion and cracking.